Many thanks for your helpful reply. I looked at pictures of Sericomyia hoverflies and could see the same special pattern on all of them, although the shapes of the insects varied a bit.

I am delighted that my weed-filled garden is providing nourishment for actual honey bees! Earlier in the year there are hordes of bumble bees of various kinds, on the bramble flowers.

Neglect and laziness do have their uses after all.

From the little I've just read about Sericomya, it seems that it tends to live in boggy areas. The shady part of the garden that I found them in did get very water-logged when there was a lot of rain earlier in the year, but would that short period be enough to draw them in? Also, I have read that they tend to live in more Northern parts of the UK rather than in London's suburbia. Does anyone know about this? I don't remember ever having seen them before.

Many thanks for pointing out that my hoverfly is Myathropa florea rather than Sericomyia. Prompted by this I’ve collected a number of photos from All About Hoverflies, by CV Duke, from www.eakringbirds.com, and from Wikipedia.

Judging by these photos, the fake bee in my photo certainly does seem to resemble Myathropa or Epistrophe melanostoma, rather than Sericomya, but it’s difficult for an untrained person such as myself to tell.

I learned other things from the sources I looked at:

The All About Hoverflies article explained that my hoverfly is probably female, as its eyes are further apart than the male's. The article has very clear photos showing this.

The eakringbirds article contained a map showing that Myathropa is more common in the south of England than in the north. I read in summer that Sericomyia is more common in the north. As I am in the south, I guess this also makes it more likely to be Myathropa.

I'm curious about Epistrophe melanostoma, as it looked very similar to Myathropa. Do you know anything about Epistrophe?

I’d like to include the photos I’ve gathered so that you can see for yourself, but I’m not sure if copyright laws would allow me to do this, so I’ve left them out. The pictures are easy to find, however, from the sources mentioned above.